Drive unit for driving at least one wheel drive shaft, in particular of a wheelset axle

ABSTRACT

The invention relates to a drive unit for driving at least one wheel drive shaft, in particular of a wheelset axle, in particular a cross-drive for use in rail vehicles with a driving engine and a transmission assembly coupled thereto; the output of the transmission assembly is formed by a hollow shaft which is coupled to the wheel drive shaft, in particular the wheelset axle, via an articulated coupling; with a braking system. The invention is defined by the following features: the braking system comprises two braking subsystems; a first braking subsystem and a second braking subsystem; the braking subsystems are embodied as disk brake systems, each comprising at least one brake disk; an attachment flange of the brake disk of a braking subsystem is embodied in integral fashion with the hollow shaft.

[0001] The invention relates to a drive unit for driving at least onewheel drive shaft, in particular of a wheelset axle, for rail vehicles,in particular having the features from the preamble of claim 1.

[0002] Such a drive unit has been disclosed by DE 4 137 233 A.

[0003] The solution described there has, however, the disadvantage thatthe necessary installation space is relatively large, which hasdisadvantageous effects particularly in vehicles of the low-platformtype. The fabrication and mounting are also relatively complex.

[0004] A similar design of a drive unit has been disclosed by U.S. Pat.No. 4,042,071 —see column 1, lines 12-14 in this document.

[0005] Drive units for rail vehicles, in particular having an integratedcross-drive, are known in a multiplicity of embodiments. These comprisea driving engine which is coupled to a transmission assembly. The driveof the transmission assembly is formed by a hollow shaft which iscoupled via an articulated coupling to the wheel drive shaft, inparticular the wheelset axle, in order to compensate the relativemovements between the wheelset axle and cross-drive. The driving engineis arranged here in the direct spatial vicinity of the transmissionassembly, preferably both—driving engine and transmission assembly—areconnected to one another by flanges in the region of their housings. Asa result of this measure, only one radial bearing is necessary for thedriving engine and a corresponding end shield. The coupling of the driveshaft of the driving engine to the transmission input shaft is carriedout by means of what is referred to as a rotationally rigid and radiallyrigid diaphragm coupling. The transmission assembly itself is usuallyembodied in two stages or in a single stage with an intermediate wheel.The output gearwheel is seated here on the hollow shaft, said outputgearwheel being either coupled fixed in terms of rotation to the hollowshaft or else forming one physical unit with said hollow shaft. Thephysical unit composed of the driving engine and transmission assembly,which is also referred to as an integrated cross-drive, is attached onlyat three points in the bogey frame with primary suspension. Ifnecessary, a braking system is assigned to the drive unit, the brakedisk being arranged on the hollow shaft. The activation elements arearranged in the housing of the transmission assembly. The disadvantageof the previous solution is that, on the one hand, the overall costs forthe structural implementation and fabrication are relatively high.Furthermore, in particular for embodiments which are to be used inlow-platform vehicles, the available radial and axial installation spaceis considerably reduced as a result of wheel diameters which arebecoming ever smaller while at the same time drive hollow shaft internaldiameters are becoming larger owing to the softer suspensions. There isthus no longer sufficient installation space available to arrange thebraking system in this region in order to achieve sufficient brakingdeceleration. Solutions for this are to arrange the braking system atanother location or else to do without conventional mechanical brakingsystems and use other braking systems, for example electrical brakingsystems, which are however more costly.

[0006] The invention has therefore been based on the object ofdeveloping a drive unit for a wheel drive shaft, in particular awheelset axle, in particular for the use of rail vehicles of the typementioned at the beginning, in such a way that sufficient brakingdeceleration is achieved with simple means and also with an axial andradial installation space which is becoming smaller and smaller. Thestructural solution is intended here to be defined by a simpleembodiment, cost-effective fabrication and mounting. Furthermore, thesolution according to the invention is to be applicable in particularfor vehicles of the low-platform type.

[0007] The solution according to the invention is characterized by thefeatures of claim 1. Advantageous refinements are given in thesubclaims.

[0008] The drive unit for driving at least one wheel drive shaft, inparticular of a wheelset axle, comprises a cross-drive with a drivingengine and a transmission assembly which is coupled thereto. The outputof the transmission assembly is embodied as a hollow shaft and isconnected to the wheel drive shaft or the wheelset axle via a coupling,in particular an articulated coupling. The braking system comprises twobraking subsystems by means of which the entirety of the braking forcenecessary can be generated by activating two braking subsystems.

[0009] The solution according to the invention provides the advantagethat as a result of the distribution between a plurality of brakingsystems said braking systems can, in their entirety, be keptrespectively smaller in terms of their dimensions in the radial andaxial directions and the installation space available can thus be usedto an optimum degree.

[0010] There are a multiplicity of ways in which the individual brakingsubsystems can be arranged. They can either be arranged on the two sidesof the transmission assembly, one of the two braking subsystems beingarranged between the transmission assembly and the first couplingelement of the coupling which is necessary for coupling to the wheelsetaxle. In order to provide the necessary braking force while taking intoaccount the necessary installation space for the individual brakingsubsystems, additional attachment means, which take up space, for theelements to be connected to one another have been dispensed with and theentire system has been structurally simplified. Here, the hollow shaftis embodied integrally with at least one of the attachment flanges forone of the braking subsystems. In a further advantageous refinement, thefirst coupling part of the articulated coupling is also embodied in onepiece with the hollow shaft. As a result, the radial installation spacenecessary for the connecting elements is significantly reduced incomparison with that in embodiments according to the prior art. Thesolution according to the invention provides the advantage that theavailable radial and axial installation space resulting from the wheeldiameters which are becoming smaller and smaller while at the same timethe output hollow shaft internal diameters are becoming larger andlarger owing to the softer suspensions is utilized to an optimum degreeand at the same makes available the necessary braking deceleration.

[0011] There are also a multiplicity of possible ways of arranging thehollow shaft and an attachment flange of a braking subsystem and/or ofthe first coupling element of the articulated coupling in an integratedfashion. Here, the embodiment can be effected in an integral fashion asa cast part or forged part. However, the specific selection depends onthe requirements of use and is at the discretion of the person skilledin the related art.

[0012] According to a further aspect of the invention, it is alsopossible to arrange both braking subsystems between the transmissionassembly and articulated coupling. In this case, both attachment flangesform one physical unit with the hollow shaft.

[0013] In one development there is provision for the transmissionhousing to be embodied in an integral fashion. The hollow shaft issupported by means of a bearing arrangement in the housing of thetransmission assembly. For the sake of simplification andstandardization there is provision for the external diameter of thebearings to be identical for all embodiment variants, while adjustmentis carried out to the requirements of use by means of variable bearingarrangement internal diameters and thus hollow shaft external diameters.

[0014] The solution according to the invention is explained below withreference to figures. They are, in particular as follows:

[0015]FIG. 1 shows an axial section of a schematic simplified view ofthe basic design of a drive unit designed according to the invention;

[0016]FIGS. 2a and 2 b show the coupling of the attachment flanges ofthe individual braking subsystems to the hollow shaft.

[0017]FIG. 1 shows a schematic simplified view of the basic design of adrive unit designed according to the invention for driving at least onewheel drive shaft which is coupled to at least one wheel and which isformed by a wheelset axle 3 in the case illustrated. The drive unit 1comprises an integrated cross-drive 4. This comprises a driving engine 5which is coupled to the transmission assembly 6. For this purpose, thedrive shaft 7 of the driving engine 5 is connected fixed in terms ofrotation to an input 8 of the transmission assembly 6, preferably via acoupling element 9 in the form of a diaphragm coupling which isrotationally rigid and embodied so as to be rigid in the radialdirection. The transmission assembly 6 comprises an output 10 which isformed by a hollow shaft 11 which encloses the wheelset axle 3 in thecircumferential direction and over at least part of its axial extent.Said hollow shaft 11 is connected to the wheelset axle 3 via anarticulated coupling 12. The articulated coupling 12 comprises here afirst coupling part 13 and a second coupling part 14 which can beconnected to one another in a rotationally elastic fashion. The firstcoupling part 13 is connected here fixed in terms of rotation to thehollow shaft 11. The second coupling part 14 is coupled at leastindirectly fixed in terms of rotation to the wheelset axle 3. Here, atleast indirectly means that the connection is made directly to thewheelset axle or else via further transmission elements, for example asecond coupling level. In one advantageous refinement, the hollow shaft11 and the first coupling part 13 are of integral design. Furthermore,the drive unit 1 comprises a braking system 15 which is preferablyembodied in the form of a disk brake unit 16.

[0018] According to the invention, the braking system 15 comprises atleast two braking subsystems 17.1 and 17.2 which are each embodied asdisk brake systems. The necessary overall braking force is thusgenerated by two braking subsystems 17.1 and 17.2. These comprise here abrake disk 18.1 or 18.2 which is only indicated and which can beattached to the hollow shaft 11. For this purpose, the hollow shaft hasin each case two attachment flanges 19.1 and 19.2 which form onephysical unit with the hollow shaft 11, and at least one flange—theattachment flange arranged between the transmission assembly 6 andarticulated coupling 12—is preferably formed with the hollow shaft 11from one component. The other second attachment flange is attached tothe hollow shaft 11 by means of attachment elements. The two attachmentflanges 19.1 and 19.2 are arranged here on both sides of thetransmission assembly 6. The activation elements (not illustrated here)can thus easily be arranged and attached to the housing 20 of thetransmission assembly. The integral embodiment of the hollow shaft 11with the simultaneously integrated attachment flange 19.1 and 19.2 forthe braking subsystems 17.1 and 17.2 and the fact that the crown gearknown from the prior art between the hollow shaft 11 and the firstcoupling part 13 provides, in addition to more cost-effectivefabrication, the advantage of requiring less radial installation space.By dispensing with the crown gear between the hollow shaft 11 and thefirst coupling part 13, less installation space is required in theradial direction for the coupling between the hollow shaft 11 and firstcoupling part 13. Furthermore, as a result of the distribution of thebraking force between two braking systems, the available radial andaxial installation space which is becoming smaller and smaller betweenthe hollow shaft 11 and the wheel diameter while at the same time thehollow shaft internal diameter D_([illegible]) is becoming larger andlarger is utilized to an optimum degree.

[0019] The driving engine 5 and the transmission assembly 6 are arrangedspatially near to one another, preferably connected to one another byflanges in the region of their housings 21 and 20. There are also amultiplicity of possible designs of the transmission assembly 6. In thesimplest case it comprises two pairs of spur wheels, a first set of spurwheels 22 and a second set of spur wheels 23. The first set of spurwheels 22 comprises a spur wheel 24 which is coupled fixed in terms ofrotation to the transmission input shaft 8, the spur wheel 24 eitherforming one integral assembly with the transmission input shaft 8 orelse being connected fixed in terms of rotation to it. The spur wheel 24intermeshes with a spur wheel 26 which is arranged on an intermediateshaft 25. Furthermore, a second spur wheel 27 is arranged on theintermediate shaft 25, said second spur wheel 27 being a component ofthe second set of spur wheels 23 and intermeshing with a spur wheel 28which is connected fixed in terms of rotation to the hollow shaft 11. Inone particularly advantageous embodiment, the hollow shaft 11 and spurwheel 28 are embodied as an integral component. In terms of fabrication,the integral component composed of the hollow shaft 11, the attachmentflange 19.2 and the first coupling part 13, and optionally also the spurwheel 28, can be embodied as a cast part or forged part. As a result, inthe case of minimum external diameter of the articulated coupling 12,here with D₁₂ and of the brake disks, here with D_(18.1 or 18.2), asimultaneously maximum internal diameter D_([illegiblel]) is possible.

[0020] According to a further aspect of the invention, the housing 20 ofthe transmission assembly 6 is embodied in an integral fashion, thebearing arrangement 29 of the hollow shaft 11 in the housing 20 having,in terms of its internal diameter D₂₈, a fine gradation with asimultaneous roller bearing external diameter D_(A28). This measureprovides a very small transmission center, i.e. transmission assembly 6with a simultaneously high roller bearing service life.

[0021] The inventive solution of the embodiment of the hollow shaft 11,attachment flange 19.2 and of the first coupling part 13 as one integralcomponent can be used for a multiplicity of integrated cross-drives 4and is not tied to a specific embodiment of the transmission assembly 6or of the driving engine 5. Other embodiments which lie within the fieldof activity of a person skilled in the respective art are alsoconceivable.

[0022] According to FIG. 2a, the attachment flange 19.2 of the secondbraking system 17.2 is embodied in an integral fashion with the hollowshaft 11. The attachment flange 19.1 of the first braking system 17.1 isconnected, as a separate component, fixed in terms of rotation to thehollow shaft 11 by means of attachment elements 30, for example in theform of screw elements which are arranged at specific intervals in thecircumferential direction of the attachment flange 19.1. A structuralembodiment of the connection of the brake disk of the second brakingsystem 17.2 to the attachment flange 19.2 is illustrated in FIG. 2a.FIG. 2b shows a possible structural embodiment of the connection of thebrake disk 18.1 to the attachment flange 19.1 of the first brakingsubsystem 17.1, and the attachment of the attachment flange 19.1 to thehollow shaft 11.

List of References

[0023]1 Drive unit

[0024]2 Wheel drive shaft

[0025]3 Wheelset axle

[0026]4 Integrated cross-drive

[0027]5 Driving engine

[0028]6 Transmission assembly

[0029]7 Drive shaft

[0030]8 Input of the transmission assembly

[0031]9 Coupling

[0032]10 Output

[0033]11 Hollow shaft

[0034]12 Articulated coupling

[0035]13 First coupling part of the articulated coupling

[0036]14 Second coupling part of the articulated coupling

[0037]15 Braking system

[0038]16 Disk brake unit

[0039]17.1 First braking subsystem

[0040]17.2 Second braking subsystem

[0041]18.1 Brake disk of the first braking subsystem

[0042]18.2 Brake disk of the second braking subsystem

[0043]19.1 Attachment flange of the first braking subsystem

[0044]19.2 Attachment flange of the second braking subsystem

[0045]20 Housing of the transmission assembly

[0046]21 Housing of the driving engine

[0047]22 First set of spur wheels

[0048]23 Second set of spur wheels

[0049]24 Spur wheel

[0050]25 Intermediate shaft

[0051]26 Spur wheel

[0052]27 Second spur wheel

[0053]28 Spur wheel

[0054]29 Bearing arrangement

[0055]30 Attachment element

[0056] D_([28]) Internal diameter of the bearing arrangement 29

[0057] D_(A28) External diameter of the bearing arrangement 29

[0058] D₁₂ External diameter of the articulated coupling

[0059] D_(18.1) External diameter of the first braking system

[0060] D_(18.2) Diameter of the second braking subsystem

1. A drive unit (1) for driving at least one wheel drive shaft (2), inparticular of a wheelset axle (3), for use in rail vehicles, having adriving engine (5) and a transmission assembly (6) coupled thereto; theoutput of the transmission assembly (6) is formed by a hollow shaft (11)which is coupled to the wheel drive shaft (2), in particular thewheelset axle (3), via an articulated coupling (12); having a brakingsystem (15); an attachment flange (19.2) for a braking subsystem (17.2)and the hollow shaft (11) are formed by one component; characterized bythe following features: the braking system (15) comprises two brakingsubsystems—a first braking subsystem (17.1) and a second brakingsubsystem (17.2); the housing (20) of the transmission assembly (6) isembodied in an integral fashion; the hollow shaft (11) is supported bymeans of a bearing arrangement (29) in the housing (20); the externaldiameter of the bearing arrangement (20) is the same for embodimentswith different external diameters of the hollow shaft (11).
 2. The driveunit (1) as claimed in claim 1, characterized in that the brakingsubsystems (17.1, 17.2) are embodied as disk brake systems (18), eachcomprising at least one brake disk (18.1, 18.2), and the attachmentflange (19.2) of the brake disk (18.2) of the one braking subsystem(17.2) and the hollow shaft (11) being formed by one component.
 3. Thedrive unit (1) as claimed in claim 1 or 2, characterized by thefollowing features: the first braking subsystem (17.1) and the secondbraking subsystem (17.2) are arranged on the two sides of thetransmission assembly (6), the second braking subsystem (17.2) beingarranged, in the installation position, between the transmissionassembly (6) and the articulated coupling (12); the attachment flange(19.1) of the first braking subsystem (17.1) being embodied as aseparate component; having means (30) for attaching the first attachmentflange (19.1) to the hollow shaft (11).
 4. The drive unit (1) as claimedin claim 3, characterized by the following features: the transmissionassembly (6) has a housing (20), the activation device of the brakingsubsystems —the first braking subsystem (17.1) and the second brakingsubsystem (17.2)—are arranged on the housing of the transmissionassembly (20) and attached.
 5. The drive unit (1) as claimed in one ofclaims 1 to 4, characterized in that the hollow shaft (11) and theattachment flange (19.2) are embodied integrally as a cast part.
 6. Thedrive unit (1) as claimed in one of claims 1 to 4, characterized in thatthe hollow shaft (11) and the attachment flange (19.2) of the secondbraking system (17.2) are embodied integrally as a forged part.
 7. Thedrive unit (1) as claimed in one of claims 1 to 6, characterized by thefollowing features: the articulated coupling (12) comprises a firstcoupling part (13) which is coupled to the hollow shaft (11) the firstcoupling part (13) is embodied integrally with hollow shaft (11).
 8. Thedrive unit (1) as claimed in claim 1, characterized in that both brakingsubsystems—first braking subsystem (17.1) and second braking subsystem(17.2) are arranged between the transmission assembly (6) and thearticulated coupling (12), and the attachement flangs (19.1, 19.2) ofthe two braking subsystems (17.1, 17.2) are embodied integrally with thehollow shaft (11).